The present invention relates to a device for the magnetic treatment of liquids and in particular to the treatment of water to reduce and prevent the buildup of scale in the pipes and vessels through which the water flows.
A problem which is quite prevalent in systems and apparatus which use large quantities of water, such as boilers, dishwashers, ice machines, and the like, is that of scale buildup on the surfaces which come into contact with the water. This problem is particularly acute in areas where the water has a high mineral content so that it is necessary for the water to be "conditioned" either by chemical action or by magnetic water treatment devices of the general type to which the present invention relates.
Examples of such magnetic treatment devices are disclosed in U.S. Pat. Nos. 3,951,807 and 4,153,559 in the name of Charles H. Sanderson. Basically, such devices comprise an elongated magnet having a multiplicity of longitudinally spaced poles encased in a non-magnetic jacket and concentrically positioned within a casing made of magnetic material, such as galvanized or black iron. The jacketed magnet may be centered by means of a pair of stepped collars secured thereto which, in turn, are centered by means of a pair of tapered inserts. Alternatively, the encased magnet may be centered by resilient sleeves which are wedged between the inner casing and the galvanized intermediate casing, or the inner casing can be centered in recesses in end fittings threadedly secured to the intermediate casing.
Magnetic treatment devices generally of this type are well known and prevent corrosion and the buildup of scale by causing the calcium and other minerals present in hard water to form, instead, a loose slurry which can be removed easily from the system by blowdown or flushing. The effectiveness with which the water is treated depends on the intensity of the magnetic field within the treatment chamber and the effective length of the chamber itself. A further consideration is that the magnetic field produced by the magnet be confined solely to the annular treatment chamber so that all of the available flux will be utilized. An important factor in ensuring this situation is to completely magnetically isolate the magnet from the supporting structure and to complete the magnetic circuit by means of a ferrous casing which surrounds the magnet and is also magnetically insulated therefrom.
In order to effectively treat the water such that the minerals therein will not form as scale on the surfaces of the pipes and vessels with which it comes into contact, it is necessary that the water be subjected to a sufficient amount of magnetic flux as it passes through the water conditioner. The degree of treatment is controlled by varying the strength of the magnet, the cross-sectional area of the annular treatment chamber, and the length of the magnet and treatment chamber. Since various installations, such as boilers, dishwashers, etc., operate at widely varying pressures and flow rates, one size of water conditioner will not be sufficient for all applications. For example, the flow rate in a large boiler will be considerably higher than in a small ice making machine, and if the same water conditioner normally used in the ice making machine were installed in the water supply line for the boiler, the drop in pressure and flow rate would be so great that proper operation of the boiler would not be possible.
In order to properly size water conditioners to the particular installation, it has been necessary to develop a number of models over a wide range of flow capacities. For example, to reduce the pressure drop, the transverse cross-sectional area of the treatment chamber has been increased. Since this results in a larger volume of water flowing through the conditioner per unit time, it is necessary to increase the diameter and, in most cases, the length of the magnet so that the water flowing through the conditioner is subjected to the same magnetic flux density per unit volume. This results in a substantial increase in the size and cost of the unit.
In installations which use all of the supply water without recirculating any of it, the water flows through the conditioner only once and it is, therefore, necessary to subject the water to the maximum level of treatment during its single pass through the conditioner. There are many systems, however, wherein the water is constantly recirculated, such as in swimming pools, vehicle radiators, air conditioning cooling towers, closed circuit boilers for heating systems, and solar panels. In a solar panel, for example, most, if not all, of the water flows through the solar collector and then either through a radiator or holding tank after which it is again pumped through the solar collector. Thus, if the water conditioner is connected in series with the solar collector, the same water is repeatedly flowing through the water conditioner where it is again subjected to the magnetic field. It has been found, however, that once the water is subjected to the proper amount of magnetic flux, it will retain its scale avoiding properties for a period of about thirty-six hours without retreatment. Accordingly, the constant retreating of the water in a system of this type is generally unnecessary. Assuming that the flow rate requirements of the system are low so that a low capacity water conditioner can be utilized, there are no significant disadvantages to continuously retreating the water, even though it is largely unnecessary.
A distinct advantage does arise, however, in the case of large flow capacity systems, such as in the cooling systems of large truck and bus engines. In such a cooling system, large volumes of water are recirculated through the radiator and at relatively low pressures. In order to accommodate the high flow rate of the water and to avoid placing a restriction in the line which would result in an unacceptable pressure drop, it would normally be necessary to utilize a water conditioner wherein the treatment chamber has a large cross-sectional area. It has been found, however, that, in systems wherein the water is continuously recirculated, it is necessary to subject only a small portion of the water to the magnetic field in any one pass through the unit. Unfortunately, prior art water conditioners having a treatment chamber which is sufficiently large to accommodate the flow requirements of a system of this type have magnets which are correspondingly large because they are designed to treat all of the water that flows through the unit. Such units are not only quite expensive, but their size prohibits their being used in certain installations, such as on vehicle engines.
Although units could be designed wherein the size and strength of the magnet is substantially reduced out of proportion with the size of the treatment chamber, this would result in decreasing substantially the magnetic flux density to which the water flowing through the chamber would be subjected. In order to avoid using a very large water conditioner but yet subject the water flowing through the conditioner to the same magnetic flux density which is appropriate for that size of treatment chamber, smaller capacity water conditioners have been connected in bypass lines connected in parallel with the main flow line of the system. This solution has proven to be extremely unsatisfactory, however, because of the difficulty in sizing the conditioner relative to the size of pipe which is to be bypassed. Additionally, there is insufficient space in many installations to accommodate the bypass line, and the additional plumbing joints necessitated by the bypass line increased the locations at which leaks can develop.
A further attempted solution is to place a full capacity water conditioner in a bypass line with a valve which is periodically opened so that the recirculating water in the closed system can be treated. This necessitates periodic maintenance of the system, however, and has proven to be unsatisfactory.